You find the worksheet in the instructions to Form 8829. Then you take the results and enter into Lacerte where the diagnostic tells you to. It's a pain in the neck.
My notes say the worksheet looks like this:
Form 8829 Line 11 Worksheet
Line 1 Unlimited State Taxes
Line 2 RE Tax on HO
Line 3 any other RE Tax
Line 4 Psnl Prop Tax
Line 5 = sum of 1-4
Line 6 = 5 x HO %
Line 7 = 2 - 6
Line 8 = 5 - 6
Line 9 = 10,000 - 8
Line 10 = smaller of 6 or 9
Carry to Line 11 of Form 8829
Line 11 = 6 - 10
Carry to Line 17 of Form 8829
